Objectives

The main objectives are:

• Study part II: to investigate the effect of a plant-based diet on micronutrient status compared to an average Danish diet

Hypotheses Study part II: it is hypothesised that the status of some micronutrients is lower after intake of a plant-based diet compared to an average Danish diet.

Participants will:

Study part II: consume either a vegan diet or an average danish diet with a high meat intake for 4 weeks. The total study period for the participants is estimated to 6 weeks (from screening to paticipants last visit)

Overall study design Study part II (n= 16 completers): A 4-week randomised parallel intervention trial comparing status of some micronutrients (with main focus on MK-9 and ferritin) after consumption of a plant-based diet compared to an average Danish diet

In study part II, participants will be randomised to either plant-based or an average Danish (meat-based) diet for 4-weeks. The participants will visit NEXS for two test days, before and after the 4-week intervention period where fasting blood will be drawn. Prior to the two test days the participants will complete a 3-day weighed dietary registration (WDR) and collect faecal and urine samples. The minimum duration for each participant will be 33days.

It is required that the participants' vitamin D status is stable. Therefore, a run-in period of up to 6-week with daily supplementation of vitamin D will be required before the first test day.

Detailed study design of part II Prerequisites Six weeks before the first test day it is required that participants have been supplemented with 10 µg vitamin D3/day (recommended daily intake) and restrain from all other types of (vitamins and mineral) supplementation. The vitamin D supplements will be provided free of charge. On day -5 (or at screening) the participants will show up at NEXS where they will receive containers and cooler bags for urine and faecal sampling. The participants will further get written and oral instructions for the WDR. Prior to Day 0, the participants will perform a 3-day WDR, collect a spot faecal sample and a 24-hour urine sample. Prior to the test day, alcohol is prohibited 48 hours before, high-intensity physical activity is prohibited 24 hours before and the participants will fast for a minimum of 12 hours before. The participants are allowed to drink ½ L of tap water during the fasting period.

Test days On Day 0, the participants will show up fasting at NEXS and one fasting blood sample will be collected (baseline blood sample). The participants will have a session with a dietician, or other delegated personnel, where they will be introduced to their assigned diets (both including daily supplementation with 10 µg vitamin D3) and asked to start the 4-week intervention. On Day 28 (±3 days), the participants will have their second test day at NEXS where one blood sample will be drawn. Prior to the second test days (Day28), they repeat the 3-day WDR, sampling of faeces and urine, and prerequisites related to alcohol intake, physical activity and fasting is required as described above.

Intervention period During the 4 weeks, the participants will show up at NEXS 1-2 days per week to receive new products and if needed they can ask for recipes, guidelines and feedback/advice from a trained dietician. Once a week they will be asked to collect a spot urine sample in the morning on the day they visit NEXS. During the third week, participants will in addition to the above mentioned also have instructions for the WDR and collections of urine and faeces repeated, and material delivered.

Inclusion Criteria:

• Men and women
• Between 18 and 65 years old (including both 18 and 65 year olds)
• Danish-speaking
• Willingness to consume/comply with consumption of study-related intervention products/diet
• Willing to take 10 µg vitamin D3/day and omit intake of all other (vitamins and mineral) supplements before and during the trial
• BMI ≤ 30.0 kg/m2
• Habitual consumption of meat at dinner minimum 5 times per week. Meat is defined as red meat and poultry, where red meat is consumed at dinner at least 2 out of 5 times per week (fish consumption is not included in the "5 per week" meat definition).

Exclusion Criteria:

• Daily smokers/users of all kinds of nicotine-containing products.
• Occasional smokers/user can be included if they are willing to refrain from all kinds of nicotine-containing products during the trial (from screening to end of trial)
• Blood donation <3 months prior to study-related blood sampling
• Intensive physical training (> 10 hours of strenuous physical activity per week)
• Participation in other clinical studies at the time of the study
• Pregnant, lactating or planning to become pregnant within the study period
• Habitual alcohol intake above current recommendation (> 10 alcoholic units/week)
• History of cancer within the past five (5) years except basal cell skin cancer and cervix
• Diagnosed with chronic inflammation disorders
• Diagnosed with gastrointestinal diseases
• Diagnosed with bone related diseases
• Diagnosed with psychiatric disorder including depression that requires medical treatment
• Medical treatment of diabetes
• Medical treatment of cardiovascular related disease
• Surgical change of the gastrointestinal tract (removal of appendix is allowed)
• Use of prescription medication that can affect their safety or impact on data
• Inability, physically or mental, to comply with the procedure required by the study protocol and evaluated by the principal investigator (PI), study manager or clinical responsible

We will report anonymized data for publications of the result.